There's a box sitting on a plank. The coefficient of static friction is 0.33. I want to figure out at which angle the box will begin to slide if the plank is tilted. I know the factors that come into play are FN, Fg or Fgx, and Fs. So far I have Fnet= FN-Fs-Fg =FN- μs-sin∅ =cos∅-0.33-sin∅ This doesn't look right... can anyone help me out?